Epsilon Archive for Student Projects

Abstract

Wild bees are indispensable pollinators of most flowering plants and agricultural crops, and thus are vital components of functioning ecosystems and provide essential ecosystem services to humans. This study primarily aimed to discover the environmental features of nesting habitat that are mostly associated with wild ground-nesting and associated cleptoparasitic bee species diversity in urban landscape. As wild bee species diversity and abundance continue to decline in the age of urban development, it is necessary to deepen our knowledge about the nesting habitat preferences of ground-nesting bees. Six environmental variables (sand patch size, age, sand grain size, soil temperature, litter cover and bare ground) were measured at ten sandy soil patches in the study area in south of Uppsala, Sweden. Colour pan traps were deployed at each site to capture wild bees on four different occasions during spring/summer of 2019. To have species data comparison even two reference sites at bee species rich sand and gravel quarries outside the city were selected for survey. It was found that highest species richness was at sand patches that had ‘medium’ compared to ‘coarse’ type of sand. Litter cover was negatively associated with species diversity. Likewise, although opposite to expectations, habitat size was negatively associated with species diversity. Sand grain size, litter cover and bare ground were the factors that shaped urban bee community. Bee data was additionally employed to assess whether cleptoparasitic bees could predict the diversity of host species and thus act as a potential indicator taxon. The results showed a positive trend, although not statistically significant. Cleptoparasitic load (CL) measure was used to assess the sand patches established specifically for insects and suggested that newly created habitats may be colonized by stable and diverse bee communities within a matter of several years. Moreover, the estimated temporal change of open sandy soil availability in the study area throughout 75-year period showed a drastic decline; less than 15% of sandy habitat was available in 2019 compared to 1945. Based on the results of this and previous studies, recommendations of additional nesting habitat creation to assist and increase wild bee diversity in urban landscape were provided.